Fluid actuated down-hole pump



Nov. 17, 1970 cs. K. ROEDER FLUID ACTUA'I'ED DOWN-HOLE PUMP 4 Sheets-Sheet 3 Filed Jan. 13, 1969 FIG. 4 i see --348 INVEN'I'OR. GEORGE K. ROEDER MARCUS L. BATES Nov. 17, 1970 e. K. ROEDER 3,540,314

FLUID ACTUATED DOWNHOLE PUMP Filed Jan. 13, 1969 4 Sheets-Sheet 4 0 4 I 34467 8 4 2 6 O 2 3 7 6% www @m w m 4 A M A/r 4 my k 1 I Inc 1 ld/ r/ I L v w I P v I] m INVENTOR. BY GEORGE K. ROEDER MARCUS L. BATES States 18 Claims ABSTRACT OF THE DISCLOSURE A fluid actuated pump assembly having a valve assembly, an engine, and a production pump. The valve assembly receives a source or power fluid from the surface of the earth. The production pump is reciprocatingly actuated by means of the engine which in turn receives a source of power fluid through the valve assembly. A piston, having a passageway therethrough, is connected to a hollow valve control rod and a hollow connecting rod. A dash pot plug in conjunction with an extension nipple and an aperture located within the valve control rod forms a path of fluid flow from the valve assembly to the bottom of the piston, thereby substantially increasing the permissible size of the piston with respect to the outside diameter of the engine cylinder. Other forms of the invention include reciprocating single and double acting pistons having the fluid flow path arranged therein in the before described manner.

BACKGROUND OF THE INVENTION Down-hole fluid operated pump assemblies, sometime called hydraulic pumping units are known in the art. These pump systems eliminate the thousands of feet of reciprocating sucker-rod required by conventional pumps in order to transmit the necessary force for the pump ing action from the surface of the ground to the bottom hole pump. The pump system of the present invention generally requires high pressure hydraulic pump which is located above the surface of the earth and which recirculates a portion of the produced fluid from the well back to the pump assembly located down-hole in the well. A valve system or assembly interconnects the high pressure fluid source with an engine to thereby move a pump shaft or pull rod which in turn enables fluid to be lifted from the production zone to the surface of the earth. This is all adequately described in my copending patent applications, Ser. Nos. 673,754 and 733,954; as well as in the prior art patents to C. I. Coberly; namely Pat. Nos. 2,081,223, 2,230,830, and 2,338,903; to which reference is made for the specific details of the valve assembly.

The various prior art devices presently available include an engine or motor end, and it is common practice to connect two production ends, or pumps, to one power piston. In hydraulic pumping units of the type used in deep wells, the operating pressure requirements of the engine increases in proportion to the required hydrostatic head, and the pressure requirements are sometime of a magnitude wherein further increase in operating pressure in order to attain a deeper well setting results in pump failure. Since the maximum operating pressure to which an engine of this nature may be subjected is limited, the only remaining design expedient available in order to extract more power from the surface hydraulic pump is to increase the area and stroke of the piston located within the engine which drives the pump. Since this latter expedient has the obvious limitation of the physical size of the piston which can be located within the cylinder of an engine, it is therefore desirable to provide a downhole pump having an engine which is designed in a manner which will enable an increase in the physical 3,540,814 Patented Nov. 17, 1970 'ice SUMMARY OF THE INVENTION The present invention relates to a down-hole fluid actuated pump assembly for use in lifting fluids from a fluid producing stratum associated with a well by utilizing hydraulic power or fluid provided from the surface of the ground and suitably conveyed to an engine associated with the pump assembly. The pump assembly generally is comprised of an elongated cylindrical unit having an upper end connected to a power fluid source, an outlet connected to a produced fluid flow conduit, and a pump inlet connected to or in communication with the fluid producing stratum. This arrangement enables the fluid produced by the stratum to be lifted to the surface of the earth along with the spent power fluid from the engine.

The present invention advantageously permits an increased diameter of piston to be utilized in the engine by eliminating the heretofore required flow passageways located within the cylinder wall within which the engine piston reciprocates. This expedient is brought about by the provision of a hollow pilot valve rod which cooperates with an extension nipple in a manner to form an annular flow passageway to one side of the engine piston while the remaining side of the engine piston is flow connected to the valve means by radially spaced apart passageways located in a radially spaced apart manner about the extension nipple and above the portion of the engine cylinder within which the piston reciprocates. Hence, the present invention eliminates the necessity for conducting fluid flow through the wall which forms the engine cylinder, thus enabling a larger cylinder bore to be incorporated within the engine than would otherwise be possible.

Another form of the present invention provides for an engine of the double acting type having a second or lower piston which is flow connected to a source of power fluid by means of a hollow connecting rod which interconnects with the first recited piston. Hence, the power fluid imposed above the main or upper piston is also imposed above the lower or second piston by a parallel flow passageway connected through the upper piston and which is interconnected to the area above the lower piston by means of the hollow connecting rod. The flow of power fluid is connected to the chamber below each piston by means of a flow passageway located within the hollow valve control rod which is conducted through the upper piston and through a pack-ofl? guide to where it is received within the lower chamber located below the lower piston. This improved pump design enables the maximum diameter of an engine piston to be utilized in driving a production pump.

Still another form of the present invention provides for a free type pump assembly having a single acting production end which is driven by an engine wherein power fluid is flow connected to the chamber above the piston on the downstroke, while spent power fluid is exhausted into the production end on the upstroke by means of the before mentioned hollow control rod, piston passageway, and hollow pull rod. The lower piston chamber remains in communication with power fluid all the time. The difference in forces exerted against the upper and lower piston faces results in sufficient energy being developed to cause reciprocation of the engine piston. This embodiment of the invention produces on the downstroke.

A still further form of the present invention sets forth a fixed or conventional hydraulic pump having a valve assembly connected to the lower piston chambers by means of the before described hollow valve rod, wherein the valve assembly alternately exhausts spent power fluid from, and conducts power fluid to each of the lower chambers. The upper piston chambers are directly and continuously in communication with produced fluid. Any number of pistons, each separated from the other by a liner seal, may be arranged in series relationship within an engine cylinder. A pull tube connects the lowermost piston to a single acting production pump.

Therefore, a primary object of this invention is to provide the engine of a down-hole pump assembly with means for increasing the piston area thereof so that power fluid can apply increased force to actuate a double acting production pump.

Another object of this invention is to provide a downhole pump assembly with an engine which utilizes a continuation of the housing of the fluid actuated pump as the engine cylinder.

A further object of the present invention is the provision of a multi-stage engine associated with a fluid operated pump assembly which eliminates the necessity of passageways being formed within the cylinder wall of the engine assembly.

Still another object of the present invention is the provision of a multi-stage pump wherein a hollow connecting rod and a hollow valve control rod is utilized to convey power fluid flow to one side of either piston.

A still further object of the present invention is the provision of apparatus which enables an improved, more powerful engine to be designed which can be utilized with existing valve assemblies and production pumps in order to increase the lifting power of the double acting pump.

Still another object of the present invention is the provision of an improved down-hole pump assembly having flow passageway means formed within the valve control rod of a single piston engine which is connected to a single acting production pump.

A still further object of the present invention is to provide an improved fluid flow path for the engine of a down-hole pump which permits the maximum size piston to be used by elimination of flow passageways from the cylinder walls.

Still another object of the present invention is the provision of a multiplicity of series connected pistons, each being actuated by power fluid being received through a hollow connecting rod.

The above objects are attained in accordance with the present invention by the provision of a fluid operated pump assembly fabricated in a manner essentially as outlined in the above summary and abstract. Other objects and advantages will become apparent to those skilled in the art as the details of construction and operation are hereinafter more fully described and claimed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view of an improved fluid actuated pump assem bly which has been fabricated essentially in accordance with the present invention; wherein, FIGS. 1A, 1B, and 1C have been broken away from each other and connected by a dashed line in the indicated manner in order to illustrate the entire pump on a single sheet of drawings;

FIG. 2 is a longitudinal cross-sectional representation of another embodiment of the present invention; wherein, FIGS. 2A and 2B are broken away from one another in the indicated manner in order to best illustrate the present invention;

FIG. 3 is a fragmentary representation of a longitudinal cross-sectional view of still another embodiment of the present invention;

FIG. 4 is a fragmentary part cross-sectional view showing the apparatus of FIG. 3 as it appears when installed down-hole in a well; and

FIG. 5 is a longitudinal cross-sectional view of another fluid actuated pump assembly made in accordance with the present invention, with FIGS. 5A and 5B being broken away from each other and connected by dashed lines in the indicated manner so as to best illustrate the essence of this embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Throughout the specification, wherever possible, like or similar numerals refer to like or similar elements.

Looking first to the details of FIG. 1, which includes FIGS. 1A, 1B and 1C, there is seen a longitudinal crosssectional view comprised of three fragmentary parts of the present invention which, when connected together along the indicated dashed line, constitutes a longitudinal cross-sectional view of one embodiment of a fluid operated pump assembly made in accordance with the present invention, as well as its operative relationship with respect to an oil well casing and production tubing. As seen in the drawings, the apparatus is comprised of a power tubing which interconnects a tubing connector 12 with a hydraulic pump (not shown) located above the surface of the earth. Nipple 14 interconnects a valve assembly with an adapter 16 which partially houses a valve control rod 18 therein which in turn actuates a valve assembly, sometime also called a control valve, as will be pointed out in greater detail later on.

An engine cylinder 20 has an engine piston 22 reciprocatingly and slidably received therein with the piston being connected to a connecting rod 24. The connecting rod is also the pull rod and is slidably received through packing gland and bushing 26 in order to reciprocate or actuate production pump 28.

Foot 30 is connected to production tubing 32, all of which is received within casing 34 which in turn communicates with formation fluid.

The valve assembly, generally indicated by the arrow at numeral 36, constitutes the upper portion of the string or down-hole pump; the engine, generally indicated by the arrow at numeral 38, constitutes the central portion of the string; and the before mentioned production pump 28 constitutes the lower portion of the string. The term string is intended to include the entire pump assembly.

Looking now more in detail to the various components of the invention, there is seen a series of radially spaced apart passageways each interconnected by one of the illustrated ports to the radially spaced apart passageways 41, although the latter could equally well be a continuous annular area circumferentially disposed about an intermediate portion of the before mentioned adapter. An upper piston cylinder chamber 42 is formed by the engine cylinder, piston, and adapter. A 'first series of radially spaced apart passageways 44 form a portion of the valve assembly and is alternately connected to either a spent power fluid outlet port 46 or the annular passageway 48 which forms an inlet for power fluid.

A second series of radial passageways 50 cooperate with a dash-pot plug 51 to provide a source of fluid flow through multiple dash-pot ports 52 and into the valve control rod annulus '54 where the fluid flow then communicates with the inside of the hollow valve rod by means of entry ports 56. A pack-off sleeve provides both a guide means and a seal means to prevent flow of fluid from the upper cylinder chamber into the annulus 54. It should be noted that entry ports 56 are never received Within the pack-off sleeve for fluid flow must always proceed therethrough. Piston passageway 62 interconnects the hollow control valve rod with the illustrated lower cylinder chamber =64. Passageway 63 continues into the production end of the pump so as to provide lubrication therefor and to provide a balance action on the end of the lower rod, as is appreciated by those skilled in the art.

Spaced apart flats 65 provided in the outer peripheral wall surface of the valve control rod serves the purpose of shifting the control valve assembly as the piston reaches its uppermost direction of travel. The valve rod upper terminal end 66 serves as the second reversing port as the piston reaches its lowermost extremity of travel. It should be noted that the hollow control rod is plugged at 66, and cognizance should be taken of this feature in view of the term hollow control rod.

Looking again now to the details of the production end of the pump assembly, wherein there is seen upper and lower exhaust ports 70, 72, respectively, from which fluid from the inlet 74 is pumped. The dual exhaust ports indicate a double acting production pump. The pump inlet is provided with a contoured lower end portion which is received within a complementary contoured pump seat 75. Formation fluid at '76 flows through the pump seat, into the pump inlet, where the double acting pump forces the fluid through the exhaust ports, whereupon the fluid then intermingles with the spent power fluid from the engine and flows within the production tubing and to the surface of the ground.

As will now be evident to those skilled in the art, the configuration of the device illustrated herein is adapted to be used in either the fixed type system as illustrated in FIG. 1, wherein the power tubing must be removed from the bore hole in order to remove the pump apparatus, or it may be used in the free pump system wherein the entire fluid actuated pump assembly is pumped through a large power fluid inlet tubing in order to either seat or retrieve the apparatus.

Looking now to the details of the next embodiment of the invention as set forth in detail in FIG. 2, the control valve assembly 136 alternately interconnects power fluid annular passageway 148 and spent power fluid outlet ports 146, respectively, to the entry ports 156 and second radially spaced apart passageways 141, respectively, to thereby force each of the illustrated double acting pistons 122, 186 to reciprocate within their respective cylinders. The entry port communicates the control rod annulus with the interior of the control rod, as in the preceding example of FIG. 1. The upper or first power piston 122 cooperates with its cylinder to form upper and lower cylindrical chambers 142 and 164. The first piston is provided with a first passageway 162 which flow connects the valve control rod with the lower cylinder chamber, while a second piston passageway 180 flow communicates the upper portion of a hollow connecting rod 163- with the upper cylinder chamber. It should be noted that the hollow connecting rod does not communicate with the hollow valve control rod.

A pack-off and guide 181 includes a sleeve 182 and a series of radially spaced apart passageways 183. The last recited passageways flow connect the lower cylinder chamber of the upper piston with a lower cylinder annulus 1194. A lower cylinder wall is reduced in size and vertically depends from the pack-off sleeve and guide where it reciprocatingly receives lower piston 186 therein.

The lower piston is connected to the lower depending end of connecting rod 163, while the lower connecting rod or pull tube 192, which is also hollow, continues from the lower piston and into the production end of the pump assembly. The pull tube cooperates With the lower cylinder to form an inner annulus 194 which is concentrically arranged with respect to annulus 194. The lower depending end of the lower cylinder is in the form of a skirt as seen at 190. A lubrication passageway 188 flow connects with the piston annulus formed between the boss 189 and the cylinder. Passageways 187 are radially spaced apart and within the lower piston so as to fluid communicate the interior of the connecting rod with the second piston cylinder upper chamber 184.

Looking now to the embodiment shown in FIGS. 3 and 4, there is seen a portion of a down-hole pump assembly of the open power oil type, which may be arranged in either the free parallel or free casing flow system. The disclosed production pump assembly includes a single action production pump which cooperates with a novel engine made in compliance with the present invention which enables the assembly to be especially adapted for use in a short cavity. The term cavity relates to the distance between the foot 330 and the O-ring collar seen at 389. The pump assembly is comprised of valve assembly 336, an engine 338, and a production end 328, with the pump end being comprised of a single acting production pump. This type pump is known to those skilled in the art. The valve assembly (not shown in FIG. 3) is actuated to a first and second position by the action of the before illustrated hollow valve rod 318, with the upper terminal end of the rod being closed as seen at 366 in FIG. 4, and in the same before described manner of FIG. 1 at numeral 66. Power fluid from the surface of the earth is conducted to the pump assembly mechanism by means of power tubing 310. The power fluid enters the engine valve assembly or the engine at either power fluid inlet 348 or 310. An extension nipple having a pack-off sleeve 3'60 reciprocatingly receives the hollow valve control rod. The hollow valve rod is provided with circumferentially disposed ports 356-, as in the before disclosed manner set forth in the embodiment of FIG. 1. Annulus 354 communicates the interior of the valve rod with the upper cylinder chamber 342 'when the piston 322 is on the upstroke. When the piston is on the downstroke, upper cylinder chamber 342 is directly connected to the source of power fluid at 348 by means of the valve assembly 336. Connecting rod 324 is provided with a hollow passageway 363 which flow connects to the before mentioned valve control rod by means of the illustrated passageway provided in the piston. Lower engine cylinder chamber 364 communicates with a multiplicity of radially spaced apart ports 310 which in turn communicates with the power fluid by means of annulus 310 formed between the pump assembly and the power oil tubing 310'.

The pull tube is reciprocatingly and sealingly received within the illustrated pack-ofl and guide 326 where the tube imparts reciprocatory motion to the single acting production pump piston 387. The lower extremity of the pull tube is provided with the illustrated ports 387 which flow connects the production pump upper chamber 385 with the interior of the connecting rod. Production exhaust ports 370 are flow connected in the usual manner to chamber 385. The exhaust ports flow communicate with annulus 370, which in turn communicates with the annulus 376 by means of production ports 372. The lower inlet 374 of the production end is received within the complementary contoured portion 375 of the foot 330. Pack-0E 331 prevents flow of fluid from the production zltlme across the foot 330, as is known to those skilled in t e art.

Looking now to the details of the embodiment set forth in FIGS. 5A and 5B, wherein there is disclosed still another modification which sets forth a novel fixed or conventional type hydraulic pump having a production end of the single action type which is driven by an engine fabricated in accordance with the present invention. The engine includes a multiplicity of spaced apart series connected pistons therein, each separated from the other to form upper and lower chambers. Power fluid inlet 410 is connected to the upper extremity of the control valve assembly 436 by the illustrated tubing connector. Adapter 416 interconnects the valve assembly with the engine cylinder 420. The lower extremity of the engine cylinder is connected to production pump 428 by the combination sub and pack-off sleeve 426. Foot assembly 430 receives the lowermost end of the pump in the before described manner of FIG. 1.

A hollow control valve rod 418 is reciprocatingly received within a pack-off sleeve 460 located on the lower marginal end portion of the illustrated extension nipple. The hollow valve control rod cooperates with the extension nipple and the adapter to provide an annulus 454. Entry ports 456 communicate the annulus with the interior 458 of the hollow rod. The upper extremity of the hollow rod is plugged and presents an upper terminal end 466 to the power fluid with the upper terminal end cooperating with the tubing connector to form annular flow passageway 448 in the same manner of FIG. 1 at 66 and 48, respectively. A series of ports 446 are connected to the annulus 454 by means of the valve assembly as previously explained in conjunction with the details of FIG. 1.

Passageway 441 communicates with port 441 rather than with annulus 454 as in the preceeding examples. A multiplicity of the radially spaced apart ports 441 communicates chamber 442 with the produced fluid at all times. Piston 422 has a series of spaced apart passageways 588 therein which flow connect passageway 458 with the chamber 464. The piston is attached to hollow connecting rod 424 and cooperates with the engine cylinder and the pack-off guide 481 to provide chamber 464. Pack-01f guide 481 separates chambers 64 and 484 from one another. Radially spaced apart ports 483 communicate the last named chamber with the produced fluid. A second piston 486, having passageways 487 and 488 therein, is rigidly afiixed to connecting rod 424 and to the solid pull rod 492.

OPERATION In operation of the first embodiment which is illustrated in FIG. 1, power fluid is continuously pumped into the tubing connector while the valve assembly alternately connects the first and second series of passageways 44 and 50 respectively, with the power fluid inlet and spent power fluid outlet 48 and 46, respectively, to thereby alternately connect the upper and lower cylinder chambers with the power fluid inlet and exhaust so as to continuously drive the piston in a reciprocating manner within the cylinder. Assuming the valve assembly to have connected the first series of passageways to the spent power fluid outlet ports while the second series of passageways are connected to the source of power fluid, the fluid flow through the engine is as follows: from the second series of passageways 50, power fluid flows to the dash-pot plug ports and into the valve control rod annulus, where the power fluid continues on to entry port 56 which interconnects the hollow valve rod with the annulus. From the hollow valve rod fluid flows through the passageways provided within the piston with the major portion of the fluid flowing into the lower cylinder chamber in order to provide power by which the piston is upstroked, or reciprocated in an upward direction. A minute amount of the power fluid continues down through the connecting rod in order to lubricate various portions of the production end, as well as to provide a balance action on the end of the lower rod. Spent power fluid from the upper cylinder chamber flows through passageways 41, passageway 40, through the first series of passageways 44, and then through the spent power fluid outlet ports at 46. As the power fluid within the lower cylinder chamber forces the piston in an upward direction, the flats seen at 65 cooperate with the remaining valve assembly to thereby cause the valve to shift to a second position, whereupon power fluid now flows through the valve and to the first series of passageways 44, while the spent fluid outlet ports are connected through the valve assembly and to the second series of passageways 50. The flow can now be traced from the source of power fluid, through the valve assembly where the flow continues through the spaced apart passageways 40, passageway 41, and into the upper cylinder chamber 42, thereby driving the piston in a downward direction.

While the piston is traveling in a downward direction, the spent power fluid is exhausted from the lower cylinder chamber to the spent power fluid outlet ports along the following path: Through the piston passageways to the inside of the hollow valve rod, through entry ports 56 and into the valve rod annulus, into the dashpot plug, through the plug ports 52 and on to the second series of passageways 50, through the valve assembly, and through the spent power fluid outlet ports. As the piston reaches its lower extremity of travel, the valve rod upper terminal end cooperates with the valve assembly to shift the valve back to its alternate position whereupon the power fluid is again connected to the second series of spaced apart passageways while the spent power fluid outlets are again connected to the first series of spaced apart passageways. The engine continues to cycle in this manner, with the valve assembly alternately connecting the power fluid inlet and spent power fluid outlet to the upper and lower cylinder chambers in response to the position of the valve control rod, thus driving the double acting piston which in turn causes the production pump to lift fluid to the surface of the ground.

It will now be appreciated by those skilled in the art that the embodiment of FIG. 1 enables the maximum piston area or piston diameter to be used in a specific size cylinder of an engine, with the engine housing now forming the engine cylinder since the heretofore necessary external fluid passageways have been eliminated by removing the passageways from the cylinder walls and placing them within the hollow control rod, thus further reducing the cylinder wall thickness a substantial amount without sacrifice of structural integrity.

In operation of the second embodiment of FIG. 2, power fluid is pumped down-hole to the pump assembly through power tubing where fluid flow continues through annulus 148 and into the valve assembly. As in the preceding example of FIG. 1, the control valve assem'bly alternately connects the power fluid to either entry port 156 or to radially spaced apart passageways 141, while the spent power fluid outlet 146 is alternately connected to either the entry port or the radially spaced apart passageways, thereby driving the double acting pistons within their respective cylinders in order to reciprocatingly actuate the production end by means of the lower pull tube, or pump connecting rod 192. It should be understood that entry port 156 corresponds to entry port 56 of FIG. 1 (which is flow connected to the second series of radially spaced apart passageways) while the radially spaced apart passageways 141 corresponds to the radially spaced apart passgeways 41 of FIG. 1 (which, is flow connected to the first series of radially spaced apart passageways 44).

Assuming the control valve to be passing fluid from the power tubing to the entry ports, the fluid then will flow into the hollow control rod, through first piston passageway 162 and into the lower cylinder chamber 164 of the upper piston, thereby forcing the upper piston in an upward direction. At the same time power fluid flow continues to flow through the passageways located within the pack-off sleeve and guide, into the lower cylinder annulus and into the lower cylinder chamber 194 of the lower piston, thereby also forcing the lower piston in an upward direction. The fluid also continues to communicate with the hollow pull tube or lower connecting rod 192 by means of lubrication passageway 188 which communicates with the annulus formed by boss 189 in order to attain the before mentioned balance action.

As the pistons jointly move toward their uppermost position, spent power fluid exits through ports 146. This expedient is effected by fluid 'within the second cylinder upper chamber flowing through lower piston ports 187, into the upper connecting rod, through second piston passageway 180, into the upper cylinder chamber of the upper piston, into passageway 141 to where the control valve assembly connects the last recited passageway to the spent power fluid outlet 146.

On the downstroke of the pistons, fluid flow from power tubing 110 is connected by the valve assembly to passageway 141, Where the power fluid enters the upper cylinder chamber 142, thereby forcing the upper piston 122 in a downward direction. At the same time, the flow continues through piston passageway 180 and into the upper connection rod, through the lower piston passageway 187, and into the second cylinder upper chamber where the power fluid forces the lower piston in a downward direction.

As each piston jointly travels in a downward direction, spent power fluid is returned to ports 146 along the following flow path: from inner annulus 194' to outer annulus 194, passageway 183, lower cylinder chamber 164, first piston passageway 162, into the hollow valve control rod, through the entry ports, through the valve rod annulus to the second series of spaced apart passageways, through the valve assembly and out of the spent power fluid outlet ports 146.

It should 'be understood that the length of the valve control rod, connecting rods, cylinders, and the like is generally much longer than as shown and illustrated in the various figures of the drawings, and that the above descriptive portion of the present disclosure is for the purpose of teaching those skilled in the art several different modes of carrying out my invention. Furthermore, both of the above embodiments are adapted for use in either the fixed type system or the free pump system.

Looking now again to the embodiment of FIGS. 3 and 4 which sets forth a free type single action pump assembly, it is noted that this embodiment is particularly adapted for use in bore holes having a sort cavity. This type production pump is often referred to as the open power oil system for the reason that the flow of power oil which operates the engine is conducted along a path which enables the spent oil from the engine to comingle with the produced fluid which is pumped or produced from the oil producing stratum of the well. The production string, that is, the tubing which transports the produced oil from the downhole pump to the surface of the ground, is arranged either parallel or concentrically with respect to the power oil tubing, as is known to those skilled in the art. While FIGS. 3 and 4 set forth a free pump casing system, it is considered within the comprehension of the present invention for those skilled in the art to arrange the apparatus in the free pump parallel system, as well as other flow configurations.

In the embodiment of FIGS. 3 and 4, power oil is pumped down-hole by means of power oil tubing 310. The power oil flows down annulus 310" where it is received within the annular passageway 348 of the pump assembly, and Within the inlet port 310. O-ring collar 389, together with the O-ring 388 and the outer peripheral wall surface of the pump sealingly cooperate together to prevent the flow of power oil further downhole. Accordingly, the flow of the power oil is isolated and must flow along the before mentioned fiow path. The production end of the pump receives oil from the production stratum through inlet 374. Since the contoured inlet portion of the pump sealingly cooperates with the contoured portion 375 of the foot, annulus 311 is separated from the production zone. Packer 331 prevents flow of fluid across the foot 330. Oil produced by the production end must therefore follow the flow path from the producing stratum, through the passageway located in the foot, into the inlet 374, where the pump piston forces the fluid through ports 370, into annulus 311, through ports 372, and into annulus 376 where the oil then flows to the surface of the ground along with the spent power fluid which comingles with the produced fluid within chamber 385.

Valve assembly 336 is moved to one of two flow positions by means of the valve control rod 318. With the valve assembly in the first of the two alternate positions, and with the piston on the downstroke, power oil flows from 348, through the valve assembly, and into chamber 10 342. It should be noted that ports 310 are arranged whereby they always communicate the lower cylinder chamber with the source of power oil, and accordingly, there is always a force exerted against the lower surface of the piston.

The difference in area between the upper and lower faces of the piston causes an unequal force to be exerted thereupon, noting that control rod end 366 is restricted to flow and together with the pull rod, represents the difference in area. Accordingly, on the downstroke, the downwardly directed force caused by the action of the oil upon the piston exceeds the upwardly directed force, and the piston travels to its lowermost position. This action causes power oil to be displaced from chamber 364 by means of ports 310. During the downstroke, check valves associated with production pump production or outlet ports and with the production piston enables the upper production chamber to fill with produced oil, as is known to those skilled in the art, and for this reason need not be further discussed in detail.

As the engine piston assumes its lowermost position of travel, the valve control rod causes the control valve to shift to its second position. This action isolates the upper engine cylinder chamber from the power fluid at 348, and at the same time connects the upper cylinder chamber to annulus 354. This action removes the force exerted by the power oil from the upper face of the piston by connecting the upper cylinder chamber to a lower pressure area, namely the pressure of the produced fluid. Since the entry ports 310 cause the lower engine cylinder chamber to remain in communication with power fluid, the differential in force exerted upon each opposed piston face causes the piston to stroke upwardly, carrying the production piston therewith because of the presence of the hollow connecting rod.

As the engine piston upstrokes, spent power fluid exhausts from chamber 342 along the following path: through the valve assembly to annulus 354, through entry ports 356, through the hollow valve control rod, through the engine piston, through the hollow connecting rod, through the spent power fluid exhaust ports 386, and into chamber 385 where the spent power fluid comingles with the produced fluid.

As the production piston upstrokes, the check valves (not shown) associated with exhaust ports 370 open, while the check valves associated with the passageway within piston 387 close, thereby enabling produced fluid and spent power fluid to flow from chamber 385 along the following before described path: through ports 370, into annulus 370, annulus 311, ports 372, and into annulus 376 where the fluid is forced to the surface of the ground.

In operation of the embodiment of FIG. 5, power fluid is received at annulus 448 where it is flow connected by the valve assembly to the annulus 454 so as to enable the power fluid to flow into the lower piston chambers 464 and 494. Power fluid is never flow connected to the upper piston chambers 442 and 484 as in the previous embodiment of FIG. 1. Instead, production fluid always communicates with the upper piston chambers by means of ports 441 and 483. As the valve assembly alternately assumes its first and second positions, power fluid is flow connected to the hollow connecting rod by means of the hollow apertured valve control rod. In one position of the valve assembly, power fluid flows into the hollow valve control rod, and in the alternate or second position of the valve assembly, the hollow valve control rod is connected to exhaust ports 446. This expedient enables spent power fluid from the lower chambers to flow or exhaust through the hollow connecting rods, through the hollow pistons, into the hollow valve control rods, into annulus 454, to where the spent power fluid comingles with the produced fluid at exhaust ports 446. Since produced fluid pressure, or the hydrostatic head of the produced fluid, is always in communication with or applied to each of the upper cylinder chambers, and since the upper terminal end 466 of the valve control rod is always subjected to the force exerted by the power fluid contained within tubing 410, the sum of these two forces are utilized to downstroke the pistons of the engine. As the engine downstrokes, spent power fluid from the lower cylinder chambers of each piston is forced to flow through the hollow connecting rods, through the valve control rod, through the valve assembly to where the spent power fluid exhausts at ports 446. On the upstroke of the engine, the valve assembly flow connects the power fluid from annulus 448 to annulus 454 where the power fluid flows through the illustrated entry ports, through the hollow valve control rod, and into each cylinder chamber by means of ports 488 and 588. Since the hydrostatic head together with the force exerted upon the upper terminal end of valve control rod provides a force which is substantially smaller than the force exerted upon the lower face of each of the pistons, this differential in force provides an action which causes the upstroke of the engine to take place. As the engine upstrokes, fluid must flow from each of the upper cylinder chambers, through ports 441 and 483, while at the same time produced fluid from the production pump flows through exhaust ports 470 and into the production annulus formed between the pump and the casing 432. Reciprocation of the single action engine continues to actuate the single action pump in this cyclic manner. Any number of pistons can be series connected in the illustrated manner of FIG. 5, with the obvious limitation of the maximum number of pistons being governed by the physical structure of the connecting rods and pull-up rod.

It should be understood that the stroke of the engine piston as well as the production piston may be of a greater length than as illustrated throughout the drawings, and for this reason the various figures of the drawings should be considered as being for the purpose of illustration only. Furthermore, the details of the valve assembly have not been extensively discussed and illustrated for the reason that those skilled in the art are familiar with various valving arrangements which accomplish this purpose, and such a valve assembly can take on several diflerent forms. Moreover, the hollow valve control rod together with the extension nipple enables various existing valve assemblies and production ends to be rearranged into a new combination of apparatus which enables a larger, more powerful engine to be used in eXisting down-hole installations, with the specific combination employed depending upon the requirements of the well in which the pump assembly is installed. For example, where the installation presents a short cavity, the single action long stroke free type pump assembly can best be used to advantage.

I claim: 1. A fluid actuated pump assembly which includes a valve assembly, an engine, and a production pump; said production pump having a formation fluid inlet conduit means and produced fluid conduit means flow attached thereto; a source of power fluid flow connected to the valve assembly; the improvement comprising:

said engine havinga piston and an engine cylinder, said piston being reciprocatingly received within said engine cylinder, said piston being spaced apart from the valve assembly; said piston dividing said engine cylinder into an upper cylinder chamber and a lower cylinder chamber; a valve control rod having a flow passageway therein, said control rod being connected between said piston and the valve assembly for controlling the fluid flow path to said engine; a connecting rod connected between said piston and the production pump for actuating the production pump;

means forming a first flow passageway from the valve assembly to said upper cylinder chamber, means forming a second flow passageway from the valve assembly into the interior of said hollow valve control rod, through said piston, and into said lower cylinder chamber;

means associated with the valve assembly for connecting said first flow passageway to conduct spent power fluid flow away from said upper chamber and to conduct power fluid flow to said second flow passageway in order to cause said piston to reciprocate in a first direction, and; said valve assembly having means associated therewith for connecting said first flow passageway to conduct power fluid flow to said upper chamber and to conduct spent power fluid flow away from said second flow passageway in order to cause said piston to reciprocate in a second direction.

2. The improvement of claim 1, and further including an extension nipple adapted to be connected to the valve assembly, said extension nipple having a free depending end located between said piston and the valve assembly, said valve control rod being reciprocatingly received within said extension nipple and forming an annular flow path therebetween for conducting fluid flow from the valve assembly, means forming an entry port in said valve control rod, seal means for preventing fluid flow from said annulus into said upper chamber;

said entry port, when in communication with the power fluid source, conducts fluid flow to said lower chamher.

3. The fluid actuated pump of claim 2 wherein an adapter is interposed between the valve assembly and said engine; said extension nipple depending from said adapter; means forming a centrally located annular passageway within said adapter, the last said passageway being coextensive with the annular passageway located within said extension nipple; said entry port being located with respect to said seal means whereby said entry port is always located in flow communication with said annulus.

4. The fluid actuated pump of claim 1 wherein said connecting rod is hollow, means flow connecting said hollow rod to said hollow valve control rod to form a flow passageway to the lower extremity of said connecting rod to thereby provide a balance action on the upstroke of said piston.

5. The fluid actuated pump of claim 1 wherein said valve control rod is provided with means forming an entry port, an extension nipple interposed between said engine and the valve assembly, said extension nipple having a lower free depending end portion, a seal in said lower free depending end portion; said entry port being located within said annulus during reciprocation of said control rod to thereby enable fluid to flow therethrough.

6. The improvement of claim 1, and further including an extension nipple connected to the valve assembly and having a free depending end located between said piston and said valve assembly, said valve control rod being reciprocatingly received within said extension nipple and forming an annular flow path therebetween for conducting fluid flow between said valve assembly and said lower chamber means forming an entry port in said valve control rod, seal means at said free depending end of said extension means; whereby said entry port conducts fluid flow from said annulus to said lower chamber;

said conecting rod being hollow and forming a passageway therethrough to thereby form a balance action on the up-stroke.

7. The fluid actuated pump of claim 1 wherein said engine includes a lower cylinder, a lower piston reciprocatingly received within said lower cylinder, said lower piston dividing said lower cylinder into a second upper cylinder chamber and a second lower cylinder chamber, said connecting rod having said piston connected thereto;

means forming a passageway from said connecting rod into said second cylinder upper chamber, means forming a passageway from said lower chamber to said second lower cylinder chamber, whereby:

both recited pistons impart motion into the production pump during operation of the engine.

8. The fluid actuated pump of claim 7 wherein a packoff guide is interposed between the first recited piston and said lower cylinder, means forming a passageway through said pack-off guide, said connecting rod being sealingly received through said pack-off guide,

said lower cylinder depending from said pack-01f guide and forming an annulus in conjunction with the first recited cylinder; said lower piston having a lower piston passageway for flow connecting said second upper cylinder chamber to the interior of said hollow connecting rod; and said lower piston having a lubrication passageway for flow connecting said lower cylinder annulus with said lower connecting rod. 9. The fluid actuated pump of claim 1, and further including a lower piston interposed in said connecting rod to thereby form a lower connecting rod;

a lower cylinder, a pack-01f guide; said lower cylinder, said lower piston, and said pack-off guide forming a second upper and a second lower cylinder chamber;

means forming a flow path from said second upper cylinder chamber to the interior of said connecting rod, means forming a flow path from said second lower cylinder chamber to said lower cylinder chamber, and means forming a flow path from said second lower cylinder chamber to the interior of said lower connecting rod.

10. A fluid actuated pump assembly having a valve assembly, an engine, and a production pump, a source of power puid flow connected to the valve assembly, the improvement comprising:

said engine having an upper and lower piston, an

upper and lower cylinder, with said upper piston being reciprocatingly received within said upper cylinder, and with said lower piston being reciprocatingly received within said lower cylinder;

means forming a hollow valve control rod, said control rod being attached to said upper piston and adapted to actuate the valve assembly for controlling the flow of fluid to and from said engine; means associated with said pistons and cylinders forming an upper cylinder chamber, a lower cylinder chamber, a second upper cylinder chamber, a second lower cylinder chamber, a connecting rod connected between said upper and lower pistons, and a pull rod connected to the production pump;

means forming a first flow passageway to enable power fluid to flow from the valve assembly to said upper cylinder chamber and to said second upper cylinder chamber; means forming a second flow passageway to enable power fluid to flow from the valve assembly to the interior of said hollow valve control rod; means forming another flow passageway from said lower chamber to said second lower chamber; and means forming a flow passageway from the interior of said control rod to one of said lower cylinder chambers;

means associated with the valve assembly for connecting said first flow passageway to conduct spent power fluid flow away from said upper chamber and to conduct power fluid flow to said second flow passageway in order to cause said piston to reciprocate in a first direction, and; said valve assembly having means for connecting said first flow passageway to conduct power fluid flow to said upper chamber and to conduct spent power fluid flow away from said second flow passageway in order to cause said piston to reciprocate in another direction.

11. The improvement of claim and further including a pack-off guide, said connecting rod being slidably received within said pack-off guide;

said cylinder freely depending from said packoff guide;

and said pull rod being connected between said lower piston and production pump.

12. The improvement of claim 11 wherein said means forming said first flow passageway includes a flow passageway connected to said upper cylinder chamber; a hollow connecting rod, means forming a passageway in said upper piston for connecting the interior of said connecting rod to said upper chamber; means forming a passageway in said lower piston for connecting said second upper chamber to the interior of said connecting rod;

said means forming said second flow passageway including a hollow valve control rod, means forming a passageway from the interior of said control rod to the valve assembly, means forming a passageway from said valve control rod to said lower cylinder chamber, passageway means associated with said pack-off guide flow connecting said second lower cylinder chamber with the first recited lower cylinder chamber.

13. A fluid actuated pump assembly having a valve assembly, an engine, a production pump including a produced fluid conduit flow connected thereto; a source of power fluid flow connected to the valve assembly; the improvement comprising:

said engine having a cylinder, a piston reciprocatingly received within said cylinder and forming upper and lower cylinder chambers; a valve control rod attached to said piston, said valve control rod having means associated therewith for causing the valve assembly to assume a first flow position and a second flow position in response to reciprocation of the piston;

an adapter connecting the valve assembly to said engine; means forming a longitudinal passageway through said adapter; said control rod being reciprocatingly received within said longitudinal passagqi way with the outer peripheral wall surface of said control rod being spaced apart from the inside peripheral wall surface of the longitudinal passageway to thereby form an annulus;

seal means for preventing fluid flow between the annulus and the upper cylinder chamber; means forming a longitudinally extending passageway of limited length within said control rod; means forming entry ports within said control rod to permit fluid to flow from the annulus into the interior of the control rod;

a connecting rod attached to said piston and oppositely disposed with respect to the control rod, said connecting rod adapted to actuate the production pump; means forming a passageway through said piston with the last recited passageway being in communication with the interior of the control rod;

whereby, spent power fluid flows from one of said cylinder chambers and along the path described by the piston passageway, the passageway within the control rod, the entry ports, the annulus, and through the valve means.

14. The improvement of claim 13 wherein there is further included an extension nipple depending from said adapter and reciprocatingly receiving said control rod therein; said extension nipple having an inside peripheral wall spaced apart from the outer wall surface of said control rod to form an annulus which is coextensive with the first recited annulus; and

said seal means being located at the lower extremity of said extension nipple.

15. The improvement of claim 13 wherein there is further included a second piston, a lower cylinder, said second piston dividing said lower cylinder into a lower piston upper chamber and a lower piston lower chamber;

said connecting rod having a lower downwardly depending portion connected between said first and second piston, a pull-rod connected to said second piston and adapted to actuate the production pump;

means flow connecting said upper chamber to said produced fluid; means flow connecting said lower chamber to said passageway through said piston;

means forming a seal between said piston and said second piston; means flow connecting said lower piston upper chamber with the produced fluid; means forming a flow passageway from said lower piston lower chamber, through said lower piston, through said connecting rod, and to the interior of said valve control rod; whereby:

the hydrostatic head of the produced fluid forces the pistons in a downward direction while the power fluid forces the pistons in an upward direction.

16. The improvement of claim 13 wherein there is further included means forming a passageway through the wall of said cylinder to thereby flow connect said lower chamber with the produced fluid;

said passageway through said piston being in cmmunication with the produced fluid within the production pump; said upper cylinder chamber having means connecting the valve means thereto when the valve means assumes a first position to thereby, exhaust spent power fluid to said production pump, and for providing power fluid to said upper cylinder chamber when the valve means assumes a second position; whereby:

power fluid drives the piston in a reciprocating manner as a result of the difference in piston area which is exposed to the power fluid.

17. The improvement of claim 16 wherein the pump assembly is of the free type, and further including;

a seal means circumferentially disposed about the outer l6 peripheral wall surface of the lower extremity of said engine, the last said seal means adapted to sealingly engage the casing of an oil well in close proximity of the production zone to thereby provide a short cavity pump.

18. The improvement of claim 13 wherein said means forming a passageway through said piston includes a flow path from said lower cylinder chamber to said annulus; whereby:

the valve means connects said upper chamber to the source of power fluid when the valve means assumes the first position; and, the valve means connects said upper chamber to the production fluid and the lower chamber to the source of power fluid when the valve means assumes the second position.

References Cited UNITED STATES PATENTS 2,366,397 1/1945 Hamer 103-46 2,726,605 12/1955 Tebbetts 103-46 2,821,141 1/1958 Sargent 103-46 2,983,227 5/1961 English 1O346 3,374,746 3/1968 Chenault 103-46 V ROBERT M. WALKER, Primary Examiner 

